The present invention relates to the field of horseshoes, and provides a horseshoe which is light in weight, yet strong enough to withstand prolonged impact stresses.
A horse is a large animal, typically weighing about 800-1400 pounds. When a horse runs at speeds up to 40 miles per hour, the load placed upon the horse's leg can exceed 15,000 pounds. Thus, the impact forces imposed on a horse's hoof, while the horse is running, can be enormous. The potential for injury to the horse is great, whenever the horse is training or racing.
Horseshoes have been used for centuries to protect the horse's hoof and to enable the horse to gallop more rapidly and more comfortably. Horseshoes have traditionally been made of metal, which is strong enough to protect the hoof. To reduce the weight and expense of the horseshoe, it has been proposed to use relatively light-weight metals such as aluminum alloys.
More recent studies of the gait of horses have shown that a horse's hoof, in the unshod natural state, will flex and widen somewhat when loaded. The use of relatively rigid, metallic horseshoes tends to prevent such natural movement, and thus impairs the horse's natural ability to absorb shocks. For this reason, it has been proposed to make horseshoes of flexible materials such as plastic, rubber, or composites, as described in U.S. Pat. No. 6,082,462, the disclosure of which is incorporated by reference herein. Horseshoes made of plastics or rubber, or the like, have not been successful, in part because they do not have the durability of metal.
The above-cited patent also describes “bonded” horseshoes, in which non-metallic materials, such as plastic or rubber, are combined with metal horseshoes in various ways. In general, such bonded horseshoes effectively provide one or more layers of plastic or rubber, in addition to the conventional metallic horseshoe. The added layer(s) will elevate the horse's hoof, beyond the elevation of the conventional horseshoe, and therefore places the horse's hoof in an unstable and more risky position, one which may be harmful to the health of the hoof.
In the prior art, it has been traditional practice to attach a horseshoe by nailing it into the hoof. However, nails can be mis-driven, and can cause damage to the hoof. This damage is apparent when the horse is seen to limp. Sometimes, a hoof is so damaged that it is nearly impossible to fasten a horseshoe with nails. Moreover, nails can wear down, and pull through the horseshoe.
The problems associated with nailing a horseshoe to a hoof can be solved, at least in theory, by attaching the shoe to the hoof with a strong adhesive, such as an epoxy. In practice, this solution has not been satisfactory. If the adhesive is strong enough to hold the horseshoe to the hoof for extended periods, then it may be very difficult or impossible to remove, especially without causing pain to the horse or damage to the hoof. If the adhesive is weak enough that the shoe can be removed without too much effort, it is usually too weak to hold the shoe in place during a period of extended use.
The present invention provides a horseshoe which has the advantages of a metal shoe, namely strength and durability, as well as the advantages of horseshoes made of flexible materials. Also, the horseshoe of the present invention does not unduly elevate the horse's hoof, and therefore does not cause injury. The horseshoe of the present invention also provides protection for the sensitive middle area of the hoof. Another aspect of the invention makes it feasible to attach a horseshoe by adhesives instead of nails.